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arXiv · 2507.20962

Survival of higher overdensity cold gas in a turbulent, multiphase medium

Ashwin Vergis George·Hitesh Kishore Das·Max Gronke
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Abstract

Cold gas clouds embedded in a hot, turbulent medium are expected to be short-lived due to disruptive hydrodynamic instabilities. However, radiative cooling might allow such clouds to survive and grow. We present 3D \texttt{Athena++} simulations of clouds with a density contrast of $\chi = 1000$, exploring turbulent Mach numbers $\mathcal{M}\in (0.25, 0.75)$ and cloud radii chosen to span cooling-to-crushing ratios $\alpha \in [0.001, 10]$. We find a shift in the survival boundary, with cloud survival occurring only when the cooling-to-cloud-crushing ratio ($t_{\text{cool,mix}} / t_{\text{cc}}$) $\lesssim 0.01$, which is lower than the expected boundary of $\sim 1$. This result shows that it is more difficult for higher over-density cold clouds to survive in a turbulent, hot medium, and suggests another `survival criterion'.

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Ashwin Vergis George, Hitesh Kishore Das, Max Gronke. 2025-07-28. Survival of higher overdensity cold gas in a turbulent, multiphase medium. https://arxiv.org/abs/2507.20962

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